Wireless signaling apparatus.



PATENTED MAY 3, 1904.

L. DE FOREST.

WIRELESS SIGNALING APPARATUS.

APPLICATION FILED MAR. 14, 1903.

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W/ TNE SSE S UNITED STATES Patented May 3, 1904.

PATENT OFFICE.

LEE DE FOREST, OF NEW YORK, N. Y., ASSIG-NOR TO THE GREATER NEW YORKSECURITY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

WIRELESS SIGNALING APPARATUS.

I SPECIFICATION forming part of Letters Patent N0. 759,216, dated May 3,1904.

Original application filed May 14, 1902, Serial No. 107,273. Divided andthis application filed March 1a, 1903. Serial To all whom, it mayconcern:

Be it known that 1, LEE DE Fonnsr, a citizen of the United States, and aresident of the city of New York, borough of Manhattan, in the countyand State of New York, have invented certain new and useful Improvementsin Wireless Signaling Apparatus, of which the following is aspecification.

My invention relates to certain improvements in wireless signalingapparatus whereby the syntonizing thereof may be better secured and theeffects of Waves non-syntonic therewith may be neutralized.

My invention consists of the novel parts and combinations thereofhereinafter described, and particularly pointed out in the claims.

This application is a division from my application for an improvement inwireless signaling devices, Serial No. 107,273, filed May 14, 1902. I

The drawings accompanying herewith show my invention embodied in formsnow preferred by me and in sufficient variety to make clear theprinciples thereof and the manner of carrying them out.

Figures 1, 2, and 3 show forms of apparatus designed to respond toeither one of two wavetrains differently periodic, but to beunresponsive to both simultaneously received and also to aperiodicwave-trains. Fig. 4 shows an apparatus designed to respond only toperiodic wave-trains of one frequency, but to be unresponsive to allothers. Fig. 5 shows a receiving apparatus designed like that of Fig. 4to respond to periodic waves of one frequency, but to be unresponsive toall other wave-trains whether periodic or aperiodic. Figs. 6 and 7 showforms of sending or wave-train-producing devices adapted to work inharmony with 4 the forms of receiving apparatus herein shown. Figs. 8and 9 are similar forms of apparatus designed to respond to wave-trainsof either of two frequencies, but to be unresponsive to wave-trains ofall other character, as well as to more than one simultaneouslyreceived.

One of the most serious troubles which has heretofore beset syntonicwireless signaling (N0 model.)

has been the inability to protect the syntonic receiving apparatus fromthe effects of aperiodic wave-trains, which by their power and 5strength are able to force vibrations in any syntonic receivingapparatus. The effect of such an aperiodic wave-train is analogous tothat of a blow given a tuning-fork, which causes it to vibrateirrespective-of any element 5 5 of time pertaining to the objectdelivering the blow. The same effect in a less degree is caused by aperiodic wave-train if of any strength. By my present invention I amenabled to protect the indicating apparatus from the disturbing effectof such wave-trains and to make it responsive only to wave-trains of thedesired frequency. I do not attempt to protect the wave-responsivedevice from the effect of such waves, but make such connec- 5 tionstherefrom to the indicatingdevices that the effect thereon will beneutral except when the wave-trains are of the designed character. Mypresent invention involves the use of two wave-responsive devices and asingle sig- 7 nal-indicating device, with which the wave-responsivedevices are connected in such a way as to oppose or neutralize eachother. Each of these wave-responsive devices is connected with awave-collector or antenna in any desired or usual manner, and saidconnection may be of a syntonic character for both or syntonic for oneand non-syntomc or aperiodic for the other.

In Fig. 1 two antennae or wave-collectors A and B are shown, eachconnected with a system of Lecher conductors of different periods,whereby a difference in syntony is ob tained. The principle and actionof these Lecher conductors are fully set forth in my 5 applicationSerial No. 97,239, liled March 8, 1902, and will not herein be repeated.1n the apparatus shown in this figure the parallel conductors b and a,extending from the base of the antenna B to the wave-responsive de- 9vice R, form one resonant syntonic system, while the conductors to andat, extending from the base of the antenna A to the wave-rcsponsivedevice-R, form another resonant syntonic system. In this case bothsystems employ a common length of conductor a, and the ground connectionis made with this conductor.

A local indicating-circuit is provided for each wave-responsive device;but only a single indicating instrument is employed, the two localcircuits being connected therewith in such manner as to oppose eachother, so that if equal effects are simultaneously received from eachcircuit the result will be that each will neutralize the other and theinstrument will not be caused to give a signal. This is true of thevarious forms of my invention herein shown.

In Fig. 1 both local circuits have a common section which contains thelocal battery Y. Choke-coils K K are also shown. The indicatinginstrument herein shown is a telephonereceiver F, having twooppositely-wound coils f and f one in each local circuit. With both ofthese equally energized no efiect will be produced in the diaphragm f,while if either be alone energized the usual telephonic effect will beproduced in the diaphragm. An aperiodic wave-train will produce equaloscillations in both of the collecting systems, and consequently willnot affect the indicating device. A periodic wave-train, if of theperiod for which either system is designed, will either affect thatsystem to the exclusion of the other or will affect that system muchmore than the other and will therefore produce an unequal effect in thetwo coils f and f thus affecting the diaphragm to give a signal. Such anapparatus is thus responsive to a single wave-train of the frequency ofeither system and is unresponsive to periodic wave-trains of otherperiods or to aperiodic wave-trains. It would also be unresponsive totwo simultaneously received periodic wave-trains corresponding inperiod, respectively, with the two systems.

The apparatus shown in Fig. 2 is like that of Fig. 1, eXcept'that thetwo systems are entirely distinct and separate. The antenna A has theLecher conductors a a, while the antenna B has the conductors 6 b. Thetwo 10- cal circuits are also entirely distinct.

The apparatus shown in Fig. 3 is like that shown in Fig. 1, except thatthe inductancecoils L and condensers G are employed to tune the systems.These may be employed in combination or separately. In fact, the methodof securing the periodicity of the receiving systems is immaterial.

In Fig. f the antenna A is shown as connected with a periodic systemconsisting of Lecher conductors a c, the period being adjusted bycondenser C. The antenna B is, however, directly connected with itswaveresponsive device R, and this system is therefore aperiodic. Anaperiodic wave train will, however, affect one system as readily asanother, which is also true of a periodic wavetrain not agreeing withthe periodic system. Neither will therefore be able to produce anyeffect upon the indicating device, while a Wave-train agreeing in periodwith the periodic receiving system will cause an unequal effect upon thecoils of the indicating device and will thus produce a signal.

In such forms as have two ground connections, such as shown in Figs. 2,3, and 4:, one of these ground connections should have a condenser Gtherein to prevent short-circuiting the local battery and yet permitfree passage of the aerial waves.

Fig. 5 shows an apparatus like that shown in Fig. A, except thatinductance-coils L are used to determine the period of the apparatus anda single antenna common to both systems is used.

Figs. 6 and 7 show forms of sending or wave-producing devices which maybe used. It is of course evident that any form of periodicwave-producingapparatus may be used as a sending or transmitting device. If, however,an aperiodic wave-producer be combined with a periodic wave producer,any form of receiving apparatus not equipped with the protective featureof my invention would be affected by the aperiodic waves emitted. Thiswould interfere with their receiving other messages, and if the emissionof such aperiodic wave-trains be made to follow each other in an orderhaving no relation to the order of the periodic wave-trains which conveythe message such unprotected receiving apparatus would be hopelesslyconfused and unable to decipher the message, even if it were adjusted tothe proper period.

Fig. 6 shows an antenna A connected with a syntonic system consisting ofLecher conductors c a. This is energized through a transformer T T froma spark-gap S, which is in a resonant circuit containing condensers Cand a circuit containing a source of electromotive force, herein shownas consisting of an alternating generator P. This last circuit isprovided with a key L, by which the duration and time of emitting thewave-trains may be controlled. The above apparatus constitutes aperiodic wave-emitting system. The antenna B is connected directly withthe circuit which contains the secondary T of the transformer, theprimary T of which is in the circuit containing a source ofelectromotive force, herein shown as an alternating generator P. In thiscase no key or other means for intermitting the series of sparks isshown. Consequently a continuous series of sparks will be emitted. Theapparatus of Fig. 7 is the same, except that one antenna only is used,it being connected with both sparking-cir cuits. Also bothsparking-circuits are connected with the same source of electromotiveforce. The key is is, however, inonly one circuit. The single commonantenna may be used in any of these devices in place of two antennaewhenever desired.

Figs. 8 and 9 show forms of apparatus which are alike, except that Fig.9 shows the threewire Lecher system and Fig. 8 the four-wire Lechersystem. The indicating device. herein shown as a telephone-receiver, isplaced in the central branch of a WVheatstone bridge. If the resistancesU U are properly proportioned, a signal is given in the receiving instrument only when one of the wave-responsive devices R or R .isaffected and not when both are affected.

It is evident that the principles of my invention may be applied to anysyntonic receiving system and is not limited to use with the formsherein shown. The kind of waveresponsive and indicating devices employedis also immaterial. Any of the well known forms of such devices may beemployed in carrylng out my invention.

Having thus descr1bed my mventlon, what I claim, and desire to secure byLetters Patcut, is

1. In a receiving apparatus for space-Sig naling, the combination with asyntonic and a non-syntonic receiving system, each containing awave-responsive device, of an indicating device connected with bothwave-responsive devices to be oppositely affected thereby.

2. In a receiving apparatus for space-signaling, the combination with asyntonic and a non-syntonic receiving system, each containing awave-responsive device, of a local indi eating-circuit for eachwave-rcsponsive device and an indicatingdevice common to both localcircuits and oppositely affected by each.

In testimony whereof I have hereunto affixed my signature, this 25th dayof February, 1903, in the presence of two witnesses.

LEE DE FOREST.

Vitnesses M. W. NOLAN, J. V. McMANUs.

